The A15 address bits is not decoded, so the ROM space is also mirrored at E800-FFFF. This is important because the 6502's reset and interrupt vectors are read from FFF8-FFFF. Since Asteroids generates a ~PMEM signal which acts as a decode for the entire program ROM space, and generates the individual ROM chip selects from that signal, this mod is particularly easy.

Concatenate a blank 2k file and the 3 ROM files in the order shown above and burn it into a 2764.

Replace the socket at F1 (PCB revisions -01 through -04) or J2 (PCB revisions -05 and -06) with a new 24-pin socket

Take a 28 pin-socket and bend out pins 1, 2, 22, 23, 27, 28

Solder a wire between pins 1, 27, 28 on the bottom of the socket, insert it into F1 / J2 and solder the other end of wire to the +5 trace (or pin 24 of DE1 / H2)

Solder a wire from pin 22 of the socket to L3:1 (~PMEM to ROM /OE)

Solder a wire from pin 2 of the socket to L3:3 (AB12 to ROM A12)

Solder a wire from pin 23 of the socket to L3:2 (AB11 tp ROM A11)

Drop the 2764 into the piggybacked socket at F1 / J2 and play more reliably!

For better aesthetics, you may prefer to solder the wires to L3 pins 1-3 and twist them together for the run to the piggybacked socket.